With the constant development of display panels, users require a higher and higher Pixels Per Inch (PPI) of the display panels. As the Virtual Reality (VR) technologies and the Augmented Reality (AR) technologies are emerging gradually, there is a higher PPI requirement for near-eye displaying thereof.
An Organic Light-Emitting Diode (OLED) display panel is expected to be predominant among future display panels due to its advantages of self-luminescence, no backlight source required, a high contrast, a small thickness, a wide angle of view, a high response speed, applicability to a flexible panel, a wide range of operating temperatures, a simple structure, a simple fabrication process, and other excellent characteristics.
The organic light-emitting diode display panel generally includes an underlying substrate, pixel driving circuits arranged on the underlying substrate, anodes arranged above the pixel driving circuits, hole injection layers arranged above the anodes, hole transport layers arranged above the hole injection layers, light-emitting layers arranged above the hole transport layers, electron transport layers arranged above the light-emitting layers, electron injection layers arranged above the electron transport layers, cathodes arranged above the electron injection layers, and encapsulation layers arranged above the cathodes. Generally a stack of the hole injection layer, the hole transport layer, the light-emitting layer, the electron transport layer, and the electron injection layer is referred to as an organic light-emitting material layer, and the anode, the organic light-emitting material layer and the cathode contact with each other. As can be apparent from the description above, the organic light-emitting diode display panel shall be driven by the pixel driving circuits to display an image. It is difficult to provide the organic light-emitting diode display panel with a high PPI as compared with a Liquid Crystal Display (LCD) panel in which each pixel is driven using only a Thin Film Transistor (TFT).
In a real design of the pixel driving circuit, a space thereof shall be extremely compressed, so longitudinally routed direct-current high-level signal lines (VDD) which are typically arranged at the same layer as data lines shall be modified to transversely routed direct-current high-level signal lines (VDD) arranged at the same layer as gate lines. For a process of the organic light-emitting diode display panel, the resistivity of molybdenum metal of the transverse direct-current high-level signal lines is far higher than the resistivity of aluminum metal of the longitudinal direct-current high-level signal lines, so a signal load on the transversely routed direct-current high-level signal lines is greatly increased. There is a signal delay due to a high load, thus greatly degrading the display quality of the organic light-emitting diode display panel.